Your reading distance and computer distance are at different distances from your face - unless you usually read at arm's length away !
Reading prescription is worked out at the distance you would normally read, so your computer prescription is usually worked out between long distance and reading.
If they didn't ask if you need to use prescription for computer use, they should have so sorry, you need to go back and tell them and they will change them at no charge. A lot of people need an extra pair of specs for computer use, believe it or not - some can accommodate the difference between the two, but some can't !
Angela Rayner lashes out and calls Sunak “pint sized loser”.